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Advanced Algebra Chapter 13. Trigonometric Ratios and FUN ctions. Right Triangle Trigonometry—13.1. Getting Started. The Greek Alphabet!. Getting Started. Right Triangles Sides Hypotenuse Adjacent Opposite Angles Right Angle Theta Other angle
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Advanced Algebra Chapter 13 Trigonometric Ratios and FUNctions
Getting Started The Greek Alphabet!
Getting Started • Right Triangles • Sides • Hypotenuse • Adjacent • Opposite • Angles • Right Angle • Theta • Other angle • The sum of all angles in any triangle is:
Getting Started • What else do we know about right triangles? • There was a guy with a theorem!
Trig • Six Trig functions • Sine • Cosine • Tangent • Cotangent • Cosecant • Secant
Evaluate all six trigonometric FUNctions for the given triangle
Evaluate all six trigonometric FUNctions for the given triangle
Evaluate all six trigonometric functions for the given triangle
Angles of Elevation or Depression • Elevation • Looking Up • Depression • Looking Down
Angles A support cable from a radio tower makes an angle of 56 degrees with the ground. If the cable is 250 feet long, how far above the ground does it meet the tower?
Angles An airplane flying at 20,000 feet is headed toward an airport. The landing systems sends radar signals from the runway to the airplane, recording a 5 degree angle of elevation. About how many miles is the airplane from the runway?
Define: • Angle • Formed by two rays sharing a common endpoint known as the vertex
Standard Position Standard Position Initial Side Terminal Side Positive v. Negative
Angles 210 degrees
Angles -45 degrees
Angles 30 degrees -330 degrees 390 degrees Coterminal Angles
Finding Coterminal Angles Two angles are coterminal iff one angle can be found my adding or subtracting multiples of 360 degrees
Coterminal Angles Find 2 positive and 2 negative angles coterminal to the following: 70 degrees 115 degrees -5 degrees
Circles What if we think about distance around a circle as a total of it’s angles? Circumference of a circle: So,
Converting from one to another… 1 Radian is how many degrees: Rewriting Degrees as Radians: Rewriting Radians as Degrees
Converting Convert 110 degrees to radians
Converting Convert radians to degrees
Why Radians? • Work great with circles • Already in terms of circumference so finding arc length is easy • What’s arc length? • Arc length (s) is the distance around a portion of a circle called a sector • What’s a sector? • Is a region of a circle bounded by two radii and the arc of the circle • The angle formed is called the central angle
Consider our Unit Circle again… Make a list of all of the x- and y-values What do you notice about these? What about pos/neg? We’ll come back to this…
Consider our Unit Circle again… Could we find a short cut to this stuff? In other words, do we need the entire circle?
Consider our Unit Circle again… • Everything we need happens in the 1st quadrant! • So, we use reference angles • Reference angle • Acute angle formed by the terminal side of the angle and the x-axis • i.e. use the shortest distance to the x-axis as your reference angle
Why reference angles and ordered pairs? • When on the unit circle: • Y-values: Sine values! • X-values: Cosine values!
Signs of Trig Functions All Students Take Calculus Sine All Tells us which values are positive Tangent Cosine
Using reference angles… • Find the sin of the following:
Using reference angles • Find cos of the following?
Using reference angles, • Find tan of the following:
Domain and Range • Domain • The numbers you plug IN to a function • Range • The numbers you get OUT of a function
Inverse FUNctions • To get an inverse, we switch the domains and ranges! • For our new function • The old range becomes our new domain • The old domain becomes our new range
Inverse FUNctions • Consider the sine function: • Domain • Range • How about inverse sine or • Domain • Range